Infectious pancreatic necrosis

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The infectious pancreatic necrosis (IPN) is an in young fish occurring, highly contagious viral disease . It is of particular economic importance for trout fish ( salmonids ), where it can cause high losses in rearing. It is a notifiable animal disease in Germany and one to be combated in Switzerland .

Pathogen

The causative agent of the IPN is the virus of infectious pancreatic necrosis from the family of the Birnaviridae .

The pathogen is widespread in Europe, America and Asia and affects both freshwater and sea fish. It can persist in latently infected fish for years, is even passed on through several generations of fish and remains infectious for longer than eight months in open water. The transmission usually takes place via the roe or milk from the parent animals to the fry. However, the virus can also be introduced into bodies of water via water, birds and contaminated equipment and food.

Clinical picture

The disease occurs particularly in young fish up to an age of 20 weeks in an acute form. Infested fish show abnormal swimming movements or lie on their side on the bottom. A dark discoloration, eyeball prolapse, distension of the abdomen and whitish strings of feces ("pseudofaeces") are common symptoms. The mortality is 10–90%.

When the abdomen is opened, inflammation and punctiform bleeding appear in the area of ​​the pyloric tubes and other internal organs. The pancreas shows necrosis . The intestine is mostly dilated, brittle and full of mucus. The liver , spleen and kidneys are often anemic and therefore pale, and the bile is accumulated.

Older animals do not get sick, but remain virus carriers and shedders for life. An exception is the Atlantic salmon , where diseases can also occur in older animals, namely when switching to salt water.

The diagnosis is made by detecting the virus.

Combat

Treatment is not possible and there is no vaccine either , so control is limited to epidemiological measures. In Germany the disease is notifiable, in Switzerland it belongs to the animal diseases of group 3.

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